Though tonight I would bench test all the electronics of the treadmill I disassembled. Everything comes on until I get to the speed control portion. It's got what I guess is a photo cell to regulate the speed by pulses. Is there a way to bypass it to make the motor run? It starts a few revolutions and then errors out and shuts down. I have a 90v PWM controller I intend to use a little later.

I would bet the board on the right in the above picture is the culprit, and that it should be possible to use the board on the left, with the SCRs and the adjustment pots as a stand-alone controller, regulated by a 5kohm or so pot. Is there any text printed on the board? Can you provide some close-ups?

I'm using the original control panel from the treadmill. It was all working well before I removed everything from the treadmill.

Here's a blury pic from last night and you can see the control panel at the top of the pic. Not too important that it work cause I will be replacing the control card with the PWM controller and it came with a speed control pot. The board on the right is the power supply. The large transformer is being used as a filter and is in series with neg side of the motor. I think without the pulse it can't figure out speed, set at control panel, and faults out. Just wanted to see how the system works while sitting on the bench.

I might find it necessary to get an 90v unregulated pwr supply to use with the PWM controller. That way I don't have to figure out how to bypass the control panel and make life a more simple using the PWM pot to regulate voltage/speed to the DC motor.

Lot's of photo's for the inquiring minds! LoL Pretty sure that if the photo cell doesn't get a pulse it is telling the controller to shut down because the treadmill belt isn't moving. (Safety feature.)

Your original controller looks like the MC-60 I got for my belt sander. If so, make sure the RPS-1 resistor is cut or removed. You don't need the board on the right. Do NOT ground the controller chassis, because you will instantly blow the thyristors. They are a pain to replace. So I hear.

SteveHGraham wrote:Your original controller looks like the MC-60 I got for my belt sander. If so, make sure the RPS-1 resistor is cut or removed. You don't need the board on the right. Do NOT ground the controller chassis, because you will instantly blow the thyristors. They are a pain to replace. So I hear.
You can find a useful file here: http://www.cnczone.com/forums/general-c ... tware.html The name of the file is MC-60modcolletion.zip. It contains a PDF of stuff about treadmill controllers.

So your saying that I won't need the old controller board on the right? So that being said I don't need to worry about cutting the RPS-1 because I'll be using the new PWM controller.

That leaves me with the question on how to by-pass all the components on the power supply board to be able to utilize the new PWM, which needs an input of 6-90vdc. I don't even see a DC voltage output of the pwr supply board. The output is an AC voltage going over to the controller. I guess it's getting rectified to DC on the controller board and on to the motor.

I am assuming the old controller is similar to an MC-60. It sure looks similar. If so, you don't need the board with the big transformer or whatever it is. You need the one with the extruded aluminum chassis with 4 things that look like Darlington transistors screwed to it. Plug AC in. Plug motor in. Plug potentiometer in. It should run just fine.

I thought it would need a transformer and a bunch of caps, but mine did not.

If you get it working, you can always save the old controller for your next motor.

SteveHGraham wrote:I am assuming the old controller is similar to an MC-60. It sure looks similar. If so, you don't need the board with the big transformer or whatever it is. You need the one with the extruded aluminum chassis with 4 things that look like Darlington transistors screwed to it. Plug AC in. Plug motor in. Plug potentiometer in. It should run just fine. I thought it would need a transformer and a bunch of caps, but mine did not. If you get it working, you can always save the old controller for your next motor. I learned JUST enough about these things to get mine to work.

You are "THE" man. That's exactly the way I made it work! Didn't even need the power supply board at all. I trimmed up the speed control pot, on the control board, to work better with added speed control pot. Full speed the motor hit 4957rpm. There's a lag from off position to bringing the rpm up to desired rpm's of maybe about 3 seconds. Is this where a PWM controller would work out better?

Now if I use a DPDT switch I can make the motor run in reverse. I reversed the motor leads and it worked great.